When I go to a category I take a quiz and when I'm done it takes me all the way back to the homepage, how do I make it stay on the same category page after I'm done doing a quiz?

I'm going to move your quiz down to the Quizzyland Forum, so you can get an answer to this. Follow me there!

As for what's happening, I think that's just a quirk of the system. (But, I may be wrong, so I'll let the other editors see if they have a better answer for you!)

The best way I have found to get round this problem is by right clicking on the quiz I want to play and then choosing the "Open in a new window" option.
When I have finished the quiz, I close the window and am back where I started.
Hope that helps.